This invention relates generally to heat exchangers and more particularly a new heat exchanger for use in an extracorporeal fluid handling system, such as a blood oxygenator or the like.
Circulating blood outside of a person's body has been a routine procedure in the operating room for several years. An important component of such a circuit is a heat exchanger used to lower the temperature of the blood prior to and during a surgical procedure and subsequently rewarm the blood to normal body temperature. The cooled blood induces a hypothermia which substantially lowers the oxygen consumption of the patient. This helps protect the body's vital organs during operative procedures which require interrupting or decreasing the circulation of blood.
A number of different structural configurations for heat exchangers have been used in the extracorporeal blood circuit including hollow metal coils, cylinders and plates through which the heat transfer fluid is circulated. U.S. Pat. No. 4,065,264 discloses a heat exchanger employing spiral tubing having spiral exterior heat exchange ribs which form in combination with a surrounding housing a spiral heat exchange passage for the blood while the heat transfer fluid flows through the tubing. This arrangement provides a very efficient transfer of heat from the blood to the transferred fluid, which is of substantial importance, since the quicker the patient's blood is cooled and rewarmed, the shorter the time the patient has to be connected to the bypass blood circuit. Nevertheless, a continual need exists for improvements in efficiency and overall performance of heat exchangers, as well as manufacturing advantages and costs.